Formaldehyde and uranyl salt treatment of protein filaments



Patented Oct. 14, 1952 i .Georgef K.1Si npso n, Ardrossan, and-John Brook s, saltcoats xscotland, assignors I to Imperial UNITED,

Chemical,Industries Limited, a corporation .of

.GreatBritain N Drawings Applicatio'n February 21,1949, Se-

rial No'. 177,676, 1948 I 1 l The present invention is concerned'withthe provision of a. method for improving the strength of artificial insolubilised protein filaments particularly of the kind wherein the insolubilisation of the coagulated filaments obtained by wet spinning is carried out by means of formaldehyde in the presence of an acidified-stronglysaline solution.

The invention is especiallyapplicable to insolubilised filaments produced from alkaline "solutions of casein and alkaline solutions of veg- .etableglobulins, for instancerpeanut globulins or soya bean globulin. solutions :in dilute 1 sodium hydroxide solution.

The object-of the .present invention is to in-' crease the strengthlof the insolubilised protein filaments so as to permit them to be readily processed in the existing machinery employed in the manufacture of textile products. V

The insolubilisation of the coagulated -wet spun protein filaments-can be most effectively or convem'ently carried out by means of formaldehyde in the presence of an acidified highly concentrated aqueous salinesolution asyforj'example, accordingto the'meth'od describedandclaimed, I

in"Britishspecification"No. 513,910 or 597,497.

The insolubilisation of the coagulated wet spun protein filaments can' also be carried'out according toBritish specificationNo. 533,952 according to which coagulated casein or vegetable seed protein filaments are treated with a concentrated aqueous solution of a salt of a hydrohalide containing formaldehyde or a compound which will yield formaldehyde under the conditions of the treatment, a salt of a reducing sulphur acid in which the atomic proportion, reckoned on the anhydrous salt, of oxygen if present, to sulphur does not exceed 2:1, and an acid which does not oxidise the salt of the sulphur acid, and which is sufficiently completely ionised in dilute aqueous solution.

While it is known that stretching of the coagulated wet spun filaments previous to their insolubilisation has a beneficial effect on the strength of the insolubilised filaments obtained In Great Britain. Aprilv 26,

have beeninsolubilised with formaldehydein the presence of acidified highly concentrated salt solution, and if desired washed to freelthem from surface and uncombined acid or formaldehyde, is obtained 1 if the insolubilised filaments-are treated, preferablynnder tension, withkani aque- Sous ,solutionof fa .uranyl salt as for, example, .uranyl acetate in acetic. acid, aqueous. solutions of saltsoi the type'of zinc uranyl acetataand .10

of uranium 1(uranyl)" salts of hydrochloric acid, nitric acid and sulphuric acid.

According to the present invehtionfitheifore, the method'ofimproving the strengthof. artifi- 'cial insolubilised filamentsof theflkind hereinbefore defined comp-rises treatingithe' insolubilised filament-s, preferably under, tension; in an aqueous solutionof' at leastone uranyl'salt.

It has been found, for instance; thatinsolubilised protein "filaments obtained according to the process of specifications No. 513,9=10',(533,952 or 597,497 when soaked'in a solution 'of'for example uranyl acetate" in 0'.1N acetic acidi produces a largeincreaseiin the rigidity. in theljwet state while the wet tensile'strengthis increased by about "30 percent. Ifhowever, atow'of-insolubilised protein ffilaments obtained "forjinstance according to the aforesaid processes" is stretched infsaid' uranyl 'acetatex'solution for about half an hour at C., then the wetlrigidity is still further increased and "the wet tensile strength is increased by about per cent and the dry tensile strength is increased by about 20 per cent. Y

The invention is illustrated by the following examples.

Example 1 A solution of ground nut protein in caustic soda is extruded into a sulphuric acid/ sodium sulphate coagulating bath. These fibres are now given an insolubilizing treatment for 16 hours at 38 C. in a solution consisting of 960 m1. brine, l0 ml. formalin, 14 ml. concentrated sulphuric acid. The fibres are now washed free from acid and dried at C. The insolubilised fibre thus obtained is now treated for 16 hours at 40 from these, and that the strength of the insolu- 45 bilised filaments can frequently be further in- Z 5 3; 7" uranyl f g f; 2 creased by treatments involving further stretchg It g; i g 1; e t 9 ing, such stretching processes as have heretofore a e ensl 8 been disclosed with respect to protein fibres not Strength of the t Fq 13 Increased only do not permitthe application of extensive by about 30% and the ngldlty, m the Wet State stretching but the effects produced are only relatively small.

We have now found that a very marked improvement in the strength of the filaments obtained from coagulated protein filaments that is considerably increased.

Example 2 A tow of fibre prepared and insolubillsed with formaldehyde as in Example 1, is stretched to a ,3 maximum in a, bath containing 3% uranyl acetate and 0.1 N acetic acid at 70 C. The stretch is maintained for half an hour and the fibre is washedjand 'dried at 105 C. The fibre produced has an" increased wet rigidity and the tensile strength is increased by about 80 It will be appreciated that the term insolubilized, as used in the foregoing specification and appended claims, refers to filaments which are not only insoluble incold water, but also are resistant to boiling water and hot dilute acids. In

other words, the insolubilized" filaments, as referred to herein, must be capable of withstanding the resistance test referred to in each of the above-mentioned British patents, .i.v er, they should be unaffected by treatment for- 90 minutes at 97 C. with a bath containing 0.1% sulfuric acid and 0.25% sodium sulfate. The filaments treated in accordance with the invention are-therefore, to

be distinguished from filaments which are simply hardened, i. e., insoluble in cold water but soluble f in boiling water and not dilute'acids.

' '1. A method of improving the strength of COaE- iilated protein filaments selected from the group" consisting of casein and vegetable globulin fila- 'f ments' which havef been insolubilized so as 'to be resistant to. boiling water and hot dilute acids, by treatmentflwith formaldehyde while in contact with an acidified highly concentrated salt solution which comprises immersing the insolubilized iilame'nts in an aqueous solution of at least one 5 uranyl salt under conditions sufficient to effect a substantial increase in the tensile strength of said filaments.

2,1The'method of claim 1, wherein the immersion is carried out under tension.

3. A method of improving the strength of coagulated protein filaments selected from the group consisting of casein and vegetable'globulin filaments which have been insolubilized so as to be resistant toboiling water and hot dilute acid, by

treatment withformaldehyde while in contact Qwith anacidified highly concentratedsalt solution which comprises immersing the insolubilized filaments in anaqueous solution of uranyl acetate and acetic acid under conditions suflicient to efi'ect a substantial increase in the tensile strength of saidillaments. L .0 2 J 4. A method of improving the strength of coagulated protein filaments selected from the group consisting of casein and vegetable globulin filaments which have been insolubilized so as to be resistant toboiling water'and hotid'ilute acid by treatment with formaldehyde while in contact with an acidified highly concentratedsalt solution which comprises immersing the insolubilized filament at a temperature of between about 40 C. and 70 C. in a solution containing 3% uranyl acetate and 0.1 N acetic acid for a time sufficient to effect a substantial increase in the tensile strength of said filaments.

5. The method of claim 4, wherein said'immer- 'sion is carried out under tension. 7, V r l r ""6."The method of claim 4, wherein said insolubilized filaments are ground nut protein filamerits.

7. The artificial insolubilized protein filaments of increased tensile strength obtained by the method of claim 1. i I I 2 GEORGE K. SIMPSON. JOI-IN BROOKS.

REFERENCES CITED The following references are of record in the file ofvithis patent:

UNITED STATES PATENTS ,Number Name Date 1,717,483 White June 18, 1929 1,799,047 Jones Man-31,1931 2,297,397: Ferretti Mar; 2, 1940 2,374,201 Highberger et al.' Apr. 24, 1945 2,438,738 Bowles "Mar. 30,1948

FOREIGN PATENTS Number Country Date 5,182 Great Britain l 1913 108,990 Austria Oct; 15, 1927 508,781 Great Britain June 26,1939

OTHER REFERENCES Progress in Leather Science, 1920 to 1945,- British Leather Manf. Research Association (page 519), July l948. (Copy in Patent Ofiice'Library and Division 43.) I Y I News Edition, American Chemical Society," November 25, 1941, article by Beal et al., pages l 1239 and 1242. 

1. A METHOD OF IMPROVING THE STRENGTH OF COAGULATED PROTEIN FILAMENTS SELECTED FROM THE GROUP CONSISTING OF CASEIN AND VEGETABLE GLOBULIN FILAMENTS WHICH HAVE BEEN INSOLUBILIZED SO AS TO BE RESISTANT TO BOILING WATER AND HOT DILUTE ACIDS, BY TREATMENT WITH FORMALDEHYDE WHILE IN CONTACT WITH AN ACIDIFIED HIGHLY CONCENTRATED SALT SOLUTION WHICH COMPRISES IMMERSING THE INSOLUBILIZED FILAMENTS IN AN AQUESOUS SOLUTION OF AT LEAST ONE URANYL SALT UNDER CONDITIONS SUFFICIENT TO EFFECT A SUBSTANTIAL INCREASE IN THE TENSILE STRENGTH OF SAID FILAMENTS. 